The different parts of the world have been supposed to be characterized by saying, that Europe has it heath lands, Asia its steppes, Africa its deserts, and America its savannahs ; but by this distinction contrasts are esta blished, that are not founded either in the nature of things, or the genius of languages. The existence of a heath always supposes an association of plants of the family of erice ; the steppes of Asia are not every where covered with saline plants; the savannahs of Venezuela furnish not only the gramina, but with these small her baceous mimosas, legumina, and other dicotyledonous plants. The plains of Songaria, those which extend between the Don and the \Volga, and the Puszta of Hungary, are real savannahs, pasturages abounding in grasses; while the savannahs to the east and west of the Stony mountains, and of New Mexico, produce chenopo diums, containing muriate and carbonate of soda. Asia has its real deserts, destitute of vegetation, in Arabia, in Gobi, and in Persia. Since we have become better acquainted with the deserts in the interior of Africa, so long and so vaguely confounded together under the name of Desert of Sahara (Zahra,) it has been observed, that in this continent, toward the east, savannahs and pastures are as in Arabia, set in the midst of naked and barren tracts. It is these last, these deserts covered with gravel, and destitute of plants, that are almost en tirely awanting in the New World. I saw them only in the low part of Peru, between Amotape and Coguimbo, on the borders of the South Sea. These are called by the Spaniards, not Llanos, but the Desiertos of Sechura and Atacarnez. This solitary tract is not broad, but 440 leagues long. The rock pierces every where through the quicksands. No drop of rain ever falls on it ; and, like the desert of Sahara, to the north of Tombuctoo, the Peruvian desert affords, near Iluara, a rich mine of rock-salt. Every where else, in the New World, there are plains, desert because not inhabited, but no real deserts.
The sante phenomena are repeated in the most dis tant regions ; and, instead of designating those vast plains, destitute of trees, by the nature of the plants they produce, it seems natural to distinguish them into deserts, and steppes or savannahs ; into bare lands with out any appearance of vegetation, and lands covered with gramina, or small plants of the dicotyledonous tribe. The savannahs of America, especially those of the temperate regions, have, in many works, been desig nated by the name prairies ; but this term L.ppears to rce little applicable to pastures that arc often very dry, though covered with grass of four or five feet in height. The lianas and the Pampas of South America are real steppes. They display a beautiful verdure in the rainy season, but in the time of great drought assume the aspect of a desert. The grass is then reduced to pow der ; the earth cracks; the alligator and the great ser pents remain buried in the dried mud till awakened from their long lethargy by the first showers of spring. These phenomena are observed in barren tracts of fifty or sixty leagues in length, wherever the savannahs are not tra versed by rivers ; for on the borders of rivulets, and around little pools of stagnant water, the traveller finds, at certain distances, even during the period of the great droughts, thickets of mauritia, a palm, the leaves of which, spread out like a fan, preserve a brilliant verdure.
The steppes of Asia are all beyond the tropics, and form very elevated table-lands. America, also, displays savannahs of considerable extent on the backs of the mountains of NI exico, Peru, and Quito; but its most extensive steppes, the Llanos of Cumana, Caraccas and Meta, are little raised above the level of the ocean, and all belong to the equinoctial zone. These circumstances give them a peculiar character. They have not, like the steppes of southern Asia, and the deserts of Persia, those lakes without issue, those small systems of rivers, that lose themselves either in the sands, or by subterraneous filtrations. The Llamas of America arc inclined towards the cast and south, and their running waters are branches of the Oroonoko.
The course of these rivers had once led me to believe that the plains formed table-lands, raised at least from one hundred to one hundred and fifty toises above the level of the ocean. I supposed that the deserts of in terior Aftica were also at a considerable height ; and that they rose one above another, like stages, from the coast to the interior of the continent. No barometer has yet been carried into the Sahara. With respect to the Banos of America, I found by barometric heights, observed at Calabozo, at the Villa del Pao, and at the mouth of the Meta, that their height is only 40 or 50 toiscs above the level of the sea. The fall of the river is extremely gentle, often nearly imperceptible ; and, therefore, the least wind, or the swelling of the Oroo noko, causes a reflux in those rivers that flow into it. The Indians believe they descend during a whole day in navigating from their mouths towards their sources. The waters that descend are separated from those that flow back by a great body of stagnant water, in which the equilibrium being disturbed, whirlpools are formed that are dangerous for boats.
The chief characteristic of the savannahs, or steppes of South America, is the absolute want of hills and ine qualities, the perfect level of every part of the soil. Often in a space of thirty leagues there is not an emi nence of a loot high. This resemblance to the surface of the ocean strikes the imagination most powerfully, where the plains are altogether destitute of palm-trees ; and where the mountains of the shore, and of the Oro nooko are so far distant, that they cannot be seen, as in the Mesa de Pavanes. The equality of surface is still more perfect in the meridian of Calabozo than towards the cast, between the Cari, La Villa del Pao, and Nueva Barcelona ; but it reigns without interruption from the mouths of the Oronooko to Lavella de Ai-aure and Os pinos, under a parallel of an hundred and eighty leagues in length ; and front San Carlos to the savannahs of Caqueta, on a meridian of two hundred leagues. It particularly characterises the new continent, as it does the low steppes of Asia, between the Borysthenes and the \Volga, between the Irtisch and the Obi. The deserts of central Africa, of Arabia, Syria, and Persia, Cobi, and Casna, present, on the contrary, many inequalities, ranges of hills, ravines without water, and rocks that pierce the sands.